Of same place



W. W. DEAN. TELEPHONE SYSTEM.

(No Model.)

No. 597,054. Patented Jan. 11,1898.

A TTOR/VEYS.

. whom-urns" wwsumo UNITED STATES V PATENT retest \VILLIAM W. DEAN, OF ST. LOUIS, MISSOURI, ASSIGNOR TO THE BELL TELEPHONE COMPANY OF MISSOURI, OF SAME PLACE.

TELEPHONE SYSTEM.

SPECIFICATION forming part of Letters Patent No. 597,054, dated January 1 1 1898.

Application filed $eptember 22,1897. $erial No. 652,539. (No model.)

To all whom it may concern.-

Be it known that I, NIL-LIAM W. DEAN, a citizen of the United States, residing at St. Louis, in the State of Missouri, have invented a certain new and useful Improvement in Telephone-Exchange Systems, (Case N o. 29,) of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawing, forming a part of this specification.

My invention relates to telephone-exchange systems, and particularly to those systems in which automatic means jointly controlled by the operators and subscribers are provided for including the calling-generators in circuit with the signal receivers or bells at the calledsubscribers stations and for removing the generators from connection with the telephone-lines when the signals have been responded to at the substations.

My invention is particularly designed for those systems in which the calling-switch for including the generator in circuit with the called-subscribers bell is normally connected with the cord-circuit and the generator coutact-anvils, as, for example, in such a system as is shown in my application for United States Letters Patent, Serial No. 610,901, filed November 3, 1896. In this system a switch is mounted on an armature of an electromagnet, said armature when unattracted, as it normally is, placing the switch in position to connect the calling-generator with the cordcircuit, so that upon inserting the connecting-plug within the called-subscribers jack signaling-current is at once directed to line. The called subscriber, upon removinghis telephone from its hook, causes an attraction of the armature and a consequent removal of the generator. The switch and generator circuits of systems of this kind are objectionable, since there is danger of leakage, the cord-circuits being normally charged. also necessary that the cord-circuit be broken between the generator and the operators telephone in order that the operator may communicate with the calling subscriber.

In. the particular system forming the subject-matter of my aforesaid application the operators are in danger of receiving shocks from the calling-generator by touching at the It issame time the tips and sleeves of the connecting-plugs.

In my present invention I provide means controlled by the connecting plug or switch for completing a normally open connection between the generator and the calling-switch normally connected with the cord-circuit.

I will explain my invention by reference to the accompanying drawing, which illustrates the preferred embodiment thereof and one of its applications. I will first give a general description of the particular system to which the invention is shown as being applied.

Two subscribers stations A B are shown. The apparatus at each station comprises a telephone switch-hook a, a signal-receiving bell a of, say, five thousand ohms resistance, transmitter c telephone-receiver a and a magneto-generator a. The telephone-hook at subscribers station A is connected with the line-spring h of the spring-jack Z) at the central office by the limb -1 of the telephoneline. The receiver (L3 is connected with the line-spring b of said spring-jack by a limb 2 of the telephone-line. lVhen the telephone is hung on the switch, as shown at station A, limbs l and 2 of the telephone-line are disconnected through the receiver. The subscriber B is similarly connected with the central office, limb 3 of the telephone-line extending from the switch-hook to the linespring 0' of the spring-jack a, while the telephone-receiver is connected with the linespring 6 of said spring-jack by a limb a of the telephone-line. The signal-bell a and magneto-generator a are likewise included in a bridge between the limbs of the telephoneline. Back contacts 13 b are engaged by the line-springs h b when said line-springs are not engaged by a plug. These back contacts form terminals of conductor 5, including the line-signal d, corresponding to substation A. Line-signal e is likewise associated with substation E. The line-signals are adapted to be operated by the magneto-generators at the substations. The plug g is the connectingplug, while the plug 71 is the answering-plug. Plug g is provided with three contact-terminals g g g adapted to engage, respectively, the short and long line springs and the thimble of each spring-jack. Plug h is provided with two contact-terminals h 71 which are adapted to engage the short and long line-springs of each spring-jack. The heel portion h of the answering-plug is preferably of insulating material. The terminals g h are adapted to be connected by a conductor 8, which is adapted to be included in circuit with contact portion 7a or in part with contact portion 2', according to the condition of use of the apparatus at the central office.

A telephone-keylis provided in a normally open bridge of the cord strands 7 and 8. -Upon operating the telephone-key the telephone may be included in a bridge-circuit between the cord strands, since the generator is disconnected from the cord-circuit. In the system of my aforesaid application it was necessary that the cord-circuit be broken between the generator and the operators telephone when the telephone was cut in.

At the central office I have shown an electromagnet comprising a core m, about which are placed two helices m m and an armature n, pivoted at it, which is adapted to be attracted by said core when energized. This armature carries plates i, 7t, and 0, which are connected with springs t, k, and 0', respectively. These springs are adapted to make contact with adjustable contact-anvils i 7?, and 0 respectively. The armature carries a spring n adapted to make contact with an adjustable contact-anvil 71 A stop 0 is provided to limit the upward movement of the armature and contact parts carried thereby. When the parts are in the normal position, as shown, the conductor 8 is broken at k and the contact-spring n removed from anvil of, while the anvils i and 0 are in contact, respectively, with the springs t" and o.

The calling-generator 13 has its terminals connected with contact-plates 1) 19 the plate 1) preferably constituting the armature of a magnet qin this instance of high resistance, as, for example, five hundred ohms. The electromagnet q has one of its terminals connected by the conductor 9 with the heel of the connecting-plug. The other terminal of said magnet is connected through the battery r with the thimbles of the spring-jacks, so that when the connecting-plug is inserted within a called-subsoribers spring-jack a local circuit is closed through the magnet, which thereupon attracts its armature and connects the generator-terminals with the anvils o t, respectively, said anvils being connected with the anvils 0 1' Thus it will be observed that when the ringing-switch, comprising the springs 0 1", is in its normal idle position and the connecting-plug is in its idle position the generator is disconnected from the cord-circuit, and that upon the insertion of a connecting-plug within a called-subscribers jack the generator is inclu dedin circuit with the called-subscriber"s bell without the operation of the ringing-switch, so that the objections heretofore enumerated are obviated.

I will now describe the means whereby the switch is actuated to remove the generator from circuit with the called-subscribers bell when the subscriber responds to the signal. The conductor 10, which connects the anvils t 7 includes the helix m. The other helix m is included in a conductor 11, having one of its terminals in the anvil n and the other connected through the battery '2- with the thimbles of the spring-jacks. The magnet and helix m are thus in a shunt relation. WVhen the connection between the ringingswitch and the generator is completed upon the insertion of the connecting-plug in the called-subscribefis jack,the helix m and generator p are included in circuit with the cord strands, the limbs of the called-subscribers telephone-line, and the signal-bell at said station. The signal-bell at the called station being of high resistance, the current from generator 2) is sufficiently reduced to prevent the helix m from energizing the core on sufficiently to attract its armature, so that the switch is still maintained in its normal position and the generator thereby maintained in circuit with the called bell. The called subscriber in response to the signal removes his telephone, whereby the current from the generator is passed through a circuit of low resistance, including the helix m, whereupon the core 712 is caused to attract its armature. As the armature is being attracted the springs n and 7c are brought into contact with anvils n and L before the springs 0 i are disconnected from the anvils o F, so that the local or independent circuit, including the coil m and battery r, is closed before the generator is removed from line. The resistances of magnet q and the helix m are so relatively proportioned that sufficient battery-current will be diverted from the magnet q to cause its deenergization and the consequent removal of the generator from connection with the ringing or calling switch.

It is obvious that other means controlled by the connecting-plug may be employed for completing the normally open connection between the source of calling-current and the switch normally connected with the cord-circuit, and I therefore do not desire to be limited to the precise means shown.

I have shown a clearing-out annunciator s of high retardation included in a bridge between the conductors 7 and 8, which is adapted to be operated by the magneto-generator at either subscribers station when conversation between the connected subscribers has been finished.

I do not wish to be limited to the precise apparatus'herein shown and described nor to the application of my invention to the particular system shown; but,

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent, is-

1. In a telephone-exchange system,the combination with a plurality of subscribers sta- ECO tions, of telephone-lines extending therefrom to the exchange, signal receivers or bells at the subscribers stations, a cord-circuit for forming a continuation of a telephone-line, a connecting-plug adapted to connect said cordcircuit and telephone-line with another telephone-line, a ringing-switch, a calling-generator, means for connecting the generator with and disconnecting it from the ringing-switch, said plug being adapted to operate or control said. means to connect the generator with the ringing-switch when it is manipulated to connect the second or called telephone-line with the cord-circuit, said ringing-switch being adapted in its normal idle position and when thus connected with the generator to direct calling-current to the bell at the called-subscribers station, means for actuating the switch to remove the generator from circuit with the bell, and apparatus at each subscribers station, each being adapted when its station is the called station to operate the latter means, substantially as described.

2. In a telephone-exchange system,the combination with a plurality of subscribers stations, of telephone-lines extending therefrom to the exchange, signal receivers or bells at the subscribers stations, a cord-circuit for forming a continuation of a telephone-line, a connecting-phi g adapted to connect the cordcircuit with a second or called telephone-line, a ringing-switch, a calling-generator, an electromagnetic circuit-changing device adapted to connect the generator with and disconnect it from the ringing-switch, suitable circuit connections whereby when said connectingplug is manipulated to connect the second or called line with the cord-circuit the operative condition of said circuit-changing device is changed to connect the calling-generator with the ringing-switch, said switch being adapted when thus connected with the generator to direct calling-current to the bell at the calledsubscribers station, means for operating the calling-switch to remove the generator from circuit with the bell and for disconnecting the generator from the ringing-switch, and apparatus at each subscribers station, each being adapted when its station is the called station to operate said means, substantially as described.

3. In a telephone-exchange system,the combination with a plurality of subscribers stations, of telephone-lines extending therefrom to the exchange, signal receivers or bells at the subscribers stations, a cord-circuit for forming a continuation of a telephone-line, a connecting-plug adapted to connect said cordcircuit and telephone-line with another telephone-line, a ringing'switch, a calling-generator, means for connecting the generator with and disconnecting it from the ringing-switch, said plug being adapted to operate or control said means to connect the generator with the ringing-switch when it is manipulated to connect the second or called telephone-line with the cord'circuit, said ringing-switch being in u adapted when moved from its normal idle position to open the circuit between the generator and bell, and means for maintaining the switch in the position to which it has been actuated, substantially as described.

4.. In a telephone-exchange system,the combination with a plurality of subscribers stations, of telephone-lines extending therefrom to the exchange, signal receivers or bells at the subscribers stations, a cord-circuit for forming a continuation of a telephone-line, a connecting-plug adapted to connect said cordcircuit and telephone-line with another or called telephone-line, a ringing-switch, a calling-generator, means for connecting the generator with and disconnecting it from the ringing-switch, said plug being adapted to operate or control said means to connect the generator with the ringing-switch when it is manipulated to connect the second or called telephone-line with the cord-circuit, said ringing-switch being adapted in its normal idle position and when thus connected with the generator to direct calling-current to the bell at the called-subscribers station, an electromagnet for actuating said switch to remove the generator from circuit with the bell, switches at each subscribers station, each subscribers switch when its station is the called station being adapted to operate said electromagnet, a circuit independent of the telephone-line which is closed by the electromagnet through itself when thus operated whereby the switch is maintained in the position to which it has been actuated, and means for opening said independent circuit operated by the cord-connectin apparatus when manipulated to disconnect the subscribers, whereby the ringing-switch is restored to its normal position, substantially as described.

5. In a telephone-exchange system,the combination with two telephone-lines each provided with a switch at the subscribers 'station thereof, a cordcircuit for forming a continuation of one of the telephone-lines, a connecting-plug adapted to connect the second or called telephoneline with the cord-circuit, a callin g-generator,a ringing-switch in its normal idle position adapted to connect the gen erator with the signal bell or receiver at the called-subscribers station when said switch is connected with the generator, an electromagnetic circuitchanging device provided with two windings or helices, one winding being connected with the generator circuit, while the other is connected in an independent circuit which contains two openings and a source of current, one of said openings being adapted to be closed by the connectingplug when manipulated to connect subscrib ers for conversation, the switch of the called subscriber when operated being adapted to reduce the resistance of the circuit containing the calling-generator to increase the current traversing the coil connected therewith, whereby the electromagnetic circuit-changing device is operated, said device when thus operated being adapted to close the other opening of the local or independent circuit and to open the connection between the generator and the coil or Winding connected therewith, and an eleotrornagnet q also included in a local circuit which is adapted to be closed by the connecting-plug when it is manipulated to connect subscribers for conversation, said eleotromagnet being adapted 10 to connect the calling generator with the ringing-switch, substantially as described.

In Witness whereof I hereunto subscribe my name this 17th day of September, A. D. 1897.

\VILLIAM \V. DEAN. lVitnesses:

WM. H. WHITE, FREDERICK J. RANLETT. 

